10.(07湖北26)
People try to avoid public transportation delays by using their own cars，and this creates further problems.
A.in short B.in case C.in doubt D.in turn
答案 D
解析 A项“简言之”；B项“以防万一”；C项“怀疑”；D项“反过来”。句意为：人们想开自己的车来避免交通耽搁，这反过来却导致了进一步的问题。
9.(07江西23)
Scientists are convinced the positive effect of laughter physical and mental health.
A.of; at B.by; in C.of; on D.on; at
答案 C
解析 be convinced of sth.坚信……；the effect on sth.对于……的影响；由此搭配形式可知C项正确。
8.(07安徽21)
The field research will take Joan and Paul about five months; it will be a long time we meet them again.
A.after B.before C.since D.when
答案 B
解析 本题考查before引导的时间状语从句的用法。主句为将来时态，从句用一般现在时态表示将来。
7.(07天津8)
It is difficult for us to learn a lesson in life we’ve actually had that lesson.
A.until B.after C.since D.when
答案 A
解析 句意为：对我们来说在生活中得到启示是很难的，直到我们真正得到了那一启示。A项为“直到”；B项为“在……以后”；C项为“自从……以来”；D项为“当……的时候”。
6.(07上海38)
Small sailboats can easily turn over in the water they are not managed carefully.
A.though B.before C.until D.if
解析 句意为：如果小帆船没有被仔细掌控好的话，那么在水中就很容易被打翻。if如果，引导条件状语从句。
5.(07上海25)
Leaves are found on all kinds of trees，but they differ greatly size and shape.
A.on B.from C.by D.in
解析 differ in在……方面不同；differ from与……不同。
4.(07北京33)
Leave your key with a neighbor you lock yourself out one day.
A.ever since B.even if C.soon after D.in case
解析 A项意为“自从……以来”，B项意为“即使”，C项意为“不久之后”，D项意为“以防；以免”。句意为：留一把钥匙给邻居，以免有一天你把自己锁在门外。
3.(07北京31)
You have failed two tests. You’d better start working harder， you won’t pass the course.
A.and B.so C.but D.or
解析 句意为：你已经两次考试不及格了，你最好更加努力学习，否则你这门课程还会不及格。or否则。
2.(07全国Ⅱ8)
he had not hurt his leg，John would have won the race.
A.If B.Since C.Though D.When
解析 本题为与过去事实相反的虚拟条件句。
1.(07全国Ⅰ31)
Between the two generations， it is often not their age， their education that causes misunderstanding.
A.like B.as C.or D.but
解析 本题结合强调句型考查并列连词词组not...but...不是……而是……，句中该并列连词词组连接主语。